Slug shooting and severe lead fouling

As I have mentioned before, I'm new in the shotgun community. Today I took my MKA to the range for the first time. I have to report that it worked without flaws and very accurate. However that's where the honeymoon ended. The barrel, choke and gas system are severely leaded. I have not seen anything like this before..!

Cleaning methods I have tried so far:

Hoppes 9 with bronze bore brush.... ha ha ha!

Break Free CLP with bronze bore brush..... seriously?

Break Free CLP with oversize nylon bore brush after 15 minutes soaking..... some lead started to come out

50% Hydrogen Peroxide and 50% Acetic Acid (White Vinegar) mixed solution soaking for 15 minutes.... now this was able to remove most of the lead from the choke and gas system components (Piston, spring, gas valve) with the help of a bronze brush.

Shooter's Choice Lead Remover with oversize nylon bore brush.... was able to clean all the gas system and choke. The barrel still is severely leaded downstream of the forcing cone area. I soaked the barrel in more solution and let the solution work overnite.... We'll see tomorrow morning.

I will like to hear from the forum how to prevent this issue or at least clean it faster, tips, advices, cleaning methods, etc....

Shooter's Choice Lead remover overnight treatment helped significantly. Last night while doing a bit more research I found out about using Chore Boy Copper Scrubber. I was fortunate enough to have some around the house so I made a small piece of it about the size of a cotton ball and push it down the barrel with the cleaning rod and 12 ga jag. Gave it about 5 passes and it was clear as new. A few patches with bore cleaner and CLP and good as new...!

I will get a bore snake and give it a try next time.

Give the Copper Scrubber a try, I was impress how easy it scrubbed lead out and been 100% copper does no harm to the chrome lined barrel.

I don't think quantity of rounds was the issue, right? Maybe the Winchester Super-X Slug?

I have considered buying a Hoppes Stainless Steel Tornado Brush but was a bit skeptical based on comments about bore wearing and scratching but I can trust your recommendation. Is it same as Brownell's?

All the high power slugs cause some leading, and you shot quite a few.

When I know I am going to shoot a bunch of slugs, sighting in or just playing, I take a bore mop and some light oil with me.
Before shooting I mop the bore with the oil, MFR7 works well and I would assume most light oils will work just as well.

After every few shots I repeat the process.
This helps a bunch to REDUCE leading, it wont stop it.
Lower power slugs produce less leading
Jim

I think that been a new shotgun the barrel needs to be polished, I will give it a good polish with KG-2 Bore Polish specially at the throat of the forcing cone. Also as Jim suggested, passing the mop in between shooting sections should control some of the fouling deposits.

For after the range clean up, I was happy with Shooters Choice Lead Remover, it made the clean up easier. But using Chore Boy Copper Scrubber was the game changer. I will prepare my own copper scrubber using an old bore brush. Also, I noticed that Midway USA has Bronze Tornado Brushes from Bore Tech, I will get some on my next order and give 'em a try.

I will like to hear your comments with regards to cleaning the Gas System. Mine was severely fouled and it was a PITA to clean.